Disc brakes are widely employed on automobiles manufactured in the past few years, particularly for the front wheels of a vehicle. Frequently, just as in the case of drum brakes, vehicle users will fail to timely replace brake linings with the result that the metal associated with holding the brake lining in place will be allowed to engage the face of a brake rotor and score the surface of the rotor. This brake rotor will then need to be resurfaced before a new lining, a disc pad, is installed. The resurfacing of brake discs has become a very substantial business, and the man-hours of labor required of operators to resurface them is tremendous.
Existing equipment is such that machining speeds are frequently limited by the tendency of rotors to vibrate or chatter. Thus, at present, with existing equipment, the typical time required to machine a single brake rotor is approximately 10 minutes. Presently known rotor lathes may employ one of several type dampening devices. In one type, magnets are simply placed on a portion of a disc to change its mass; in another, a band of flexible material is wrapped around the outer periphery of a disc; in a third, one or two fabric-type materials are frictionally biased against the surface of a rotor, being held by fixed mounted arms; and finally, it is understod that in one, a pivotally coupled hardware member is imposed against the face of a rotor at a fixed location. Significantly, the existing devices have not enabled chatter-free machining at rates which enable a rotor to be machined in significantly less than about 10 minutes.
A still further problem is that with existing machinery, discs are mountable in a single direction, and this results in a machined spiral thread-like surface on each side of a disc wherein the spiral threads toward the center of the disc in the same direction for each brake disc. Since two discs from a pair of opposite wheels of a vehicle are mounted on the vehicle in a right-hand and left-hand manner, the spiral-like surfaces react oppositely on the pads of opposite wheels. This lack of symmetry can produce an unbalance in braking effects on opposite wheels, and in some instances produce undesired vibrations.
It is an object of this invention to provide a basically new configuration for brake lathes which substantially decreases the vibration problem, enabling a reduction in machining times by a factor of from 15 to 25, thus tremendously reducing the labor costs in the servicing or machining of disc brake rotors. A further object is to provide a brake lathe adapted to resurface both left and right wheel rotors at one time and in such a manner that the spiral threads produced rotate in the same direction on right-hand and left-hand wheels of a vehicle, thus accompanying cost reduction with enhanced quality of workmanship.